I know I will sound like a prude...and maybe I am...but that part of the body is for another part for procreation by a penis...and not far from that wonderous place where life begins, is where the exit shoot is for what the body needs to remove. Having a face and tongue buried in there or close to the vicinity of the dumping grounds is begging for someone to get something they don't want. Like cancer of the throat, mouth and tongue.
Same goes for blow jobs. It was not made for a mouth and sperm was not made for the stomach.
Yes ma'am, that is a tad prudish.
And still, I must admit...
my tongue has swung the bung.